Calipers



(No Model.)

R. CRITTENDEN & G. HENRY.

OALIPERS.

No. 278,225. Patented May 221883.

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UNITED STATES PATENT OFFICE.

RALPH CRITTENDEN, OF HARTFORD, AND ROBERT Cr. HENRY, OF W'ATER- BURY, CONNECTICUT.

CALIPERS.

SPECIFICATION forming part of Letters Patent No. 278,225, dated May 22, 1883.

Application filed March 22, 1883. (No model.)

. ters of reference marked thereon.

Our invention relates especially to that class of calipers employed in fine work, andhas for its object the production of a device which may be quickly and accurately adjusted,

- and of such shape and construction as to be 2 is a vertical longitudinal section.

carried in the pocket with ease and safety.

To this end our invention consists, essentially, in bows of the usual shape pivoted in a.

slotted head upon a suitable shank. The bows are each provided with a short arm extending downward within the slotted 'head through a sliding shaft, which is operated by means of a nut at the extremity of the shank opposite to the slotted head. A slot is formed in the sliding shaft or bar, wherein is fitted a gib, held in place against the short arms by means of a spiral spring, said spring taking up all the back-slack as the arms are opened.

In the drawings, Figure l is a View in side elevation of our improved calipers, and Fig. Fig. 3 is an enlarged cross-sectional view at line to aof Fig. 2.

Like letters of reference, wherever they occur, indicate corresponding parts in all. the figures.

A are the bows of the calipers, pivoted upon a rivet, a, passing through the slotted head B of shank C. A' short arm, at, having rounded or curved edges extends from each bow A, as shown. These arms are about one-half the thickness of the bows and overlap each other.

D is a slotted shaft, passing through shank C. Said shaft isvenlarged and provided with a slot at-d, within which the arms a play. A spiral spring, E, is coiled around shaft D, and finds a hearing at one extremity against a gib, dgwhioh presses against the arms a. Theother extremity of the spring bears against a shoulder, 0, upon the interior of shank C. Shaft the bows open gradually, all back-slack being taken up by the spring as the shaft advances.

If desired, a gage may be affixed to the calipers in order to facilitate setting toany predetermined width.

Having now fully described our. invention, what we claim as new therein, and desire to secure by Letters Patent, is

1. In calipers, the bows provided with short arms projecting into the slotted head of a shank wherein said bows are pivoted, the width between the points ofthe bows being regulated by means of a slotted shaft passing through the hollow shank of the instrument, said shaft having a slot therethrough at one extremity, wherein is located a gib engaging with the short arms of the bows and with a spring, the other extremity of the shaft bearing a screw-thread upon which a thumb-nut plays, substantially as shown and described.

2. In calipers 0f the character herein specified, the combination, with the short arms of the bows, of the gib in the slotted shaft, and a spiral spring coiled around said shaft, substantially as and for the uses and purposes shown and described.

3. In an instrument of the character herein specified, bows A, having short arms a, hollow shank C, bearing slotted head 13, slotted shaft 1), gib of, spring E, and thumb-nut F, the whole combined and arranged to operate substantially as shown and described.

In testimony that we claim the foregoing 

